Ultrasonic transducers receive electrical energy as an input and provide acoustic energy at ultrasonic frequencies as an output, or receive acoustic energy at ultrasonic frequencies as an input and provide electrical energy as an output. An ultrasonic transducer can include a piece of piezoelectric material that changes size in response to the application of an electric field. If the electric field is made to change at a rate comparable to ultrasonic frequencies, then the piezoelectric element can vibrate and generate acoustic pressure waves at ultrasonic frequencies. Likewise, when the piezoelectric element resonates in response to impinging ultrasonic energy, the element can generate electrical energy.